The present invention relates generally to double acting hydraulic cylinders operating in conjunction with double-acting feedback cylinders and more particularly to cylinders having integral feedback cylinders.
In the past, hydraulic feedback of the cylinder rod position was accomplished by connecting a separate feedback cylinder in parallel with the hydraulic work cylinder, and where equal volume feedback was required, a double rod cylinder was used. Typical of these feedback systems which incorporated double rod cylinders is the U.S. Pat. No. 2,236,467 granted to E. C. S. Clench on Mar. 11, 1939.
These systems have the disadvantages of requiring additional space above that necessary for the work cylinder alone, additional parts for mounting the feedback cylinder, and additional design effort to establish feedback cylinder positioning and operational geometry.